1. Field of the Invention
The present invention relates to a method and system for monitoring the instantaneous behaviour and interaction with the road of a tire during the running of a motor vehicle equipped with tires.
2. Description of the Related Art
A tire of a motor vehicle, when rolling on a road surface, is subject to a vertical load and to tangential and transverse external forces, which are generated in the various manoeuvres, such as braking, acceleration, cornering, straight line running etc.
During each manoeuvre, any point on the tire rolling in steady state and in transitory conditions carries out a movement, which can be represented by displacements in the three spatial directions, for each cycle of the revolution of the tyre. The movement of any points have characteristics which are typical of the position of each particular point of the structure, of the external profile of the tyre, of the conditions of use (speed, load and pressure), of the conditions of the surface on which the tyre rolls, and of the external forces to which the tyre is subjected in the manoeuvres of braking, acceleration, cornering, etc.
The patent application EP887211 describes a tire monitoring system for a tire on a vehicle comprising: a sensor device operatively arranged with respect to the tire to create an electrical pulse during the footprint pass corresponding to a deformation of the tire; means for calculating a ratio of the duration of said electrical pulse to the duration of one tire revolution; means for transmitting said ratio to an evaluating unit placed in the vehicle. Said sensor device is placed within the tread area of said tire in order that said electrical pulse presents a first maximum at the entrance and a second maximum at the leaving of said footprint pass.
The patent application WO0136241 in the name of the same applicant of present application describes a method for monitoring the instantaneous behaviour of a tyre during the running of a motor vehicle, comprising the steps of    acquiring and storing, at least temporarily, at least one basic reference curve which represents the variation of the displacement of at least one specified point of the said tyre in at least one spatial direction, as a function of the spatial position of the point, in at least one portion of a revolution of the tyre,    continuously acquiring signals of the position in space of the specified point of the tyre,    deriving from the position signals at least one cyclic curve of operating displacement of the point in the spatial direction, as a function of the spatial position of the point, in at least one portion of a revolution of the tyre,    continuously comparing the said curve of operating displacement with the said basic reference curve of displacement, and    emitting a signal depending on the comparison and indicating the instantaneous behaviour of the tyre.
The patent U.S. Pat. No. 6,204,758 describes a tire monitor for use in a remote tire monitor system including an accelerometer for detecting acceleration of the tire monitor. Location (relative to vehicle) information for the tire monitor is determined in response to the acceleration. In this manner, tire location (relative to the vehicle) information is determined automatically to allow the system to display tire characteristic data such as air pressure in conjunction with tire location (front right, front left).